Catalyst compositions for polyaliphatic isocyanate-based polyurethanes and process for their use

ABSTRACT

A catalyst composition for improving the reaction-cure rate of polyurethane compositions derived from poly aliphatic isocyanate compounds and poly-hydroxyl bearing compounds is disclosed. The catalyst composition consists essentially of 
     (a) from about 25 to about 75 parts by weight of lead naphthenate; and 
     (b) from about 75 to about 25 parts by weight of at least one dialkyltin dicarboxylate compound of the formula: ##STR1##  wherein R is selected from C 1  to C 8  alkyl and R&#39; is selected from C 1  to C 18  alkyl, based upon 100 parts by weight of said catalyst composition. 
     The catalyst compositions promote sufficiently rapid cure rates such that injection moldable poly aliphaticisocyanate-based polyurethane compositions may be provided. In a preferred embodiment, new and improved integral skin foam polyurethane compositions are disclosed which may be reaction injection molded to form integral skin foam shaped articles exhibiting ultraviolet light resistance and improved colorability.

CROSS REFERENCE TO RELATED APPLICATION

This is a division of application, Ser. No. 568,159, filed Jan. 4, 1984,now U.S. Pat. No. 4,548,919, which is a continuation-in-part ofcopending application Ser. No. 450,626, filed Dec. 17, 1982 and nowabandoned.

BACKGROUND OF THE INVENTION

The present invention relates to catalyst compositions effective toaccelerate curing of aliphatic-isocyanate-based polyurethanecompositions. More particularly, it relates to new and improved catalystcompositions consisting essentially of synergistic mixtures of anorganic tin compound and an organic lead compound and to an improvedmethod of curing polyurethane compositions employing these catalystcompositions. The present invention also relates to new and improvedintegral skin foam polyurethane compostions and to improved methods formaking useful shaped articles therefrom.

In this application, the term "aromatic isocyanate" refers to an organicisocyanate compound wherein the isocyanate group(s) are bonded directlyto a carbon atom of an aromatic nucleus. By "aliphatic isocyanate" ismeant an organic isocyanate compound wherein the isocyanate group orgroups are bonded directly to an aliphatic carbon atom. The termpolyaliphatic isocyanate means a compound having more than onealiphatic-isocyanate linkage in one molecule.

Generally, polyurethane resins and products are obtained by reactingisocyanate compounds and hydroxyl-bearing compounds to form urethanegroups in accordance with the equation:

    RNCO+R'OH→RNHCOOR'

Polyurethane resins are formed by reaction of polyfunctional startingmaterials containing isocyanate and hydroxyl groups.

Polyurethane resins and articles prepared therefrom are extremely usefulbecause upon curing they can be flexible or rigid and articles preparedtherefrom are generally characterized by good solvent resistance,abrasion resistance, impact resistance and colorability.

It is presently known to use polyurethanes to form integral skin foamarticles which comprise a core of microcellular foam and a skin which iseither microcellular or non-cellular. The prior art polyurethaneintegral skin foam compositions generally comprise an aromaticisocyanate, such as bis(isocyanatophenyl)methane, a polyol, and afoaming agent. Aromatic isocyanates have been employed because of theirhigh reactivity and rapid cure times. These compositions are castable toform elastomeric articles or may be injection molded in one step inaccordance with reaction injection molding (RIM) techniques. The outersurfaces of the skins of these shaped articles can be provided with manyand varied decorative features imparted by the inner surfaces of thecasting or injection molds, to simulate the appearance of leather orwood materials and the like. Polyurethane integral skin foam productshave therefore been extensively used in furniture, automobile,electronics and footwear applications.

A serious disadvantage encountered with these polyurethane compositionsand integral skin foam products prepared therefrom is that polyurethanesbased on aromatic isocyanates have extremely poor ultraviolet lightstability and undesirable yellowing or other discoloration develops withthese materials upon exposure to sunlight or other sources ofultraviolet light. In the past, where these compositions were utilizedto form colored products, such as, cushions, armrests, seat backs or thelike, they had to be colored to an intense shade, or to a dark shade orto black, to hide the undesirable discoloration of the resin. If it wasnecessary or desired to provide light or brightly colored articles, thearticles had to be prepared with a separate non-urethane colored coatinglayer or had to be dipped or otherwise coated with an ultraviolet lightresistant protective layer. These additional coating and productionsteps are expensive and inefficient in large scale productionoperations.

More recently, aliphatic isocyanate compounds and polyurethanecompositions incorporating them have been developed. The aliphaticisocyanates and their preparation are suitably disclosed in U.S. Pat.Nos. 2,723,265 and 3,290,350. Polyurethane compositions based on thesealiphatic compounds are known to have excellent ultraviolet lightstability and do not discolor upon exposure to sunlight and othersources of ultraviolet radiation. However, the aliphatic isocyanates areconsiderably less reactive than the aromatic isocyanates. Extendedreaction times render aliphatic-isocyanate based polyurethanecompositions generally unsuitable for reaction injection moldingapplications because molding cycle times need to be prohibitively longand the integral skin foam products ultimately obtained are generallysoft and exhibit less than desirable strength and load-supportingcapability.

Many catalysts have been employed in an effort to accelerate the rate ofreaction between aliphatic isocyanates and hydroxyl-containingcompounds. Organic lead salts and organic tin salts are two of the morecommonly used catalyst materials herefore employed for this purpose.Neither of these catalysts however, when used alone at any reasonableconcentration, is effective to adequately accelerate the reactionbetween secondary and tertiary aliphatic isocyanates andhydroxyl-containing compounds at temperatures below about 100° C., whichmeans that lead catalysts and tin catalysts when used singly are notsufficiently effective to provide a satisfactory RIM moldable aliphaticisocyanate-based polyurethane integral skin foam composition.

In U.S. Pat. No. 4,150,206, a reaction injection moldable polyurethaneintegral skin foam composition based on an aliphatic isocyanate isdisclosed. The compositions are described as possessing a reactivitylevel substantially similar to the reactivity of aromatic isocyanates.The compositions comprise a polyol, an aliphatic isocyanate, a minoramount of water and a synergistic catalyst combination selected from thefollowing catalyst mixtures:

(i) an amine containing a structure, ##STR2## and a salt, alcoholateand/or phenolate of an alkali metal or alkaline earth metal;

(ii) an organic lead compound and a primary or secondary amine;

(iii) an organic lead compound and an amine containing the structure##STR3## or (iv) an organic lead compound and a salt, alcoholate orphenolate of an alkali metal or alkaline earth metal.

It is disclosed in said patent that if one of the above-identifiedcatalyst mixtures is present, that satisfactory reaction rates suitablefor RIM processes are obtained and that other catalysts such as tincatalysts, may be added if desired.

Unexpectedly, in view of the foregoing, it has now been discovered thatthe rate of reaction between aliphatic isocyanate compounds and hydroxylcontaining compounds is surprisingly improved by the incorporation of acatalyst composition consisting essentially of certain synergisticmixtures of lead naphthenate and dialkyltin dicarboxylates in specifiedproportions, said catalyst compositions being added in carefullyspecified amounts.

SUMMARY OF THE INVENTION

In accordance with the present invention, new and improved compositionsfor catalyzing the reactions between polyaliphatic-isocyanate compoundsand organic compounds containing a plurality of hydroxyl groups consistessentially of a mixture of

(a) lead naphthenate and

(b) at least one dialkyltin dicarboxylate compound of the formula:##STR4## wherein R is C₁ to C₈ alkyl and R' is C₁ to C₁₈ alkyl, theweight ratio of lead naphthenate to said dialkyltin dicarboxylate insaid mixture being from about 25:75 to about 75:25.

The synergistic catalyst mixtures of the present invention unexpectedlyand surprisingly are effective to significantly reduce the reaction-curetime of a poly aliphatic-isocyanate based polyurethane composition, ascompared with the cure times obtained with an organic lead compound oran organic tin compound used alone. Generally, the new and improvedcatalyst mixtures of the present invention are added to polyaliphatic-isocyanate based polyurethane compositions in minor effectiveamounts on the order of from about 0.01 to 10 parts by weight, basedupon 100 parts by weight of the aliphatic isocyanate andhydroxyl-bearing reactants, preferably from about 0.05 to about 5.0parts by weight, based on the weight of the isocyanate and hydroxylcontaining reactants, and especially preferably, from about 2.0 to about6.0 parts by weight based upon 100 parts by weight of thehydroxyl-bearing reactants.

In accordance with another aspect of the present invention, highlyreactive, rapidly curable polyurethane compositions are provided, saidcompositions comprising:

(a) a mixture or a prepolymer of:

(i) a poly aliphatic isocyanate compound of the formula: ##STR5##wherein R and R' are each, independently, selected from hydrogen, alkylor substituted alkyl and x is a bridging means selected from aliphatic,cycloaliphatic or aromatic groups, or a prepolymer adduct of saidisocyanate compound possessing polyaliphatic isocyanate functionality;and

(ii) a monomeric or polymeric compound containing a plurality ofhydroxyl groups; and

(b) a minor effective amount of a catalyst composition thereforconsisting essentially of a mixture of:

(i) from about 25 to about 75 parts by weight of lead naphthenate; and

(ii) from about 75 to about 25 parts by weight of a dialkyltindicarboxylate compound of the formula: ##STR6## wherein R is selectedfrom C₁ to C₈ alkyl and R' is selected from C₁ to C₁₈ alkyl, based upon100 parts by weight of said catalyst composition.

The rapidly curable poly aliphatic isocyanate-based polyurethanecompositions of this invention, containing effective amounts of thesynergistic catalyst compositions described herein, exhibit sufficientlyrapid cure times such that the compositions may be effectively employedto provide useful shaped articles by high speed casting and reactioninjection molding techniques.

In accordance with a preferred embodiment of this aspect of theinvention, new and improved reaction injection moldable integral skinfoam polyurethane compositions are provided. These new and improvedintegral skin foam compositions comprise:

(a) an aliphatic disocyanate compound of the formula: ##STR7## wherein Rand R' are each independently, selected from hydrogen, alkyl andsubstituted alkyl and X is a bridging means selected from divalentaliphatic, cycloaliphatic or aromatic groups, or a prepolymer adduct ofsaid isocyanate compound possessing poly aliphatic isocyanatefunctionality;

(b) a mixed polyol component comprising:

(i) from about 50 to about 100 parts by weight of a vinylmonomer-grafted polyether polyol having a hydroxyl value of about 20 toabout 60; and

(ii) from about 50 to about 0 parts by weight of a polyether polyolhaving an hydroxyl value of about 20 to 60, per 100 parts by weight ofsaid polyol mixture;

(c) an effective amount of a crosslinking agent, said crosslinking agentcomprising mixture of an amino alcohol and ethylene glycol or a lowmolecular weight adduct of ethylene oxide and a polyol compound in aweight ratio of from about 1:3 to 3:1, respectively;

(d) a minor effective amount of a catalyst composition therefor, saidcatalyst composition consisting essentially of:

(i) from about 25 to about 75 parts by weight of lead naphthenate; and

(ii) from about 75 to about 25 parts by weight of an organic tindicarboxylate compound of the formula ##STR8## wherein R² is selectedfrom C₁ to C₈ alkyl and R³ is selected from C₁ to C₁₈ alkyl; and

(e) a foaming agent, wherein the molar ratio of the total isocyanategroups in (A) to the total of hydroxyl groups in (B) and (C) combined isfrom about 1:0.9 to about 1:1.2, respectively.

The present invention also relates to methods of preparing highlyreactive, rapidly curable poly aliphaticisocyanate based polyurethanecompositions, to methods of preparing injection moldable integral skinfoam poly aliphatic isocyanate-based polyurethane compositions and tomethods of making shaped articles from these integral skin foampolyurethane compositions.

Other object and advantages of the present invention will becomeapparent from, the following detailed description and illustrativeworking examples.

DETAILED DESCRIPTION OF THE INVENTION

It has been discovered that certain combinations, or mixtures, of leadnaphthenate and dialkyl tin dicarboxylates provide enhanced reactionrates between hindered aliphatic secondary and/or tertiary isocyanatesand compounds containing a plurality of hydroxyl groups. Moreparticularly, it has been discovered that certain combinations of leadnaphthenate and dialkyltin dicarboxylates are synergistic and providereaction-cure rates several times faster than are obtained with eithercatalyst component alone.

The catalyst compositions of the present invention consist essentiallyof a mixture of:

(i) about 75 to about 25 parts by weight of lead naphthenate; and

(ii) about 25 to about 75 parts by weight of a dialkyl tin dicarboxylatecompound of the formula: ##STR9## wherein R is selected from C₁ to C₈alkyl and R' is selected from C₁ to C₁₈ alkyl, per 100 parts by weightof said catalyst composition.

The dialkyltin dicarboxylates are well known catalyst compounds per se.The preferred dialkyltin dicarboxylates for use herein are dimethyltindilaurate and dibutyltin dilaurate. The lead naphthenate/dialkyltindicarboxylate catalyst compositions of the present invention may, ingeneral, be effectively employed to promote the reaction and cure ofpoly-aliphatic isocyanate compounds and hydroxyl-bearing compounds inconcentrations of from about 0.01 to about 10.0 parts by weight, andpreferably about 0.05 to about 5 parts by weight, based upon 100 partsby weight of the isocyanate and hydroxyl-bearing compounds combined.

In accordance with this aspect of the invention, new and improved highlyreactive, rapidly curable polyurethane compositions are provided, saidcompositions comprising:

(a) a mixture or a prepolymer of

(i) a monomeric or polymeric compound possessing aliphatic isocyanatefunctionality; and

(ii) a monomeric or polymeric compound containing a plurality ofhydroxyl groups; and

(b) a minor effective amount of a catalyst composition thereforconsisting essentially of the lead naphthenate/dialkyltin dicarboxylatecomposition described above.

The poly aliphatic-isocyanate compounds for use herein as component (a)(i) may be monomeric or polymeric compounds having a plurality ofaliphatic isocyanate terminal groups. More particularly, component (a)(i) may comprise at least one poly aliphatic isocyanate compound of theformula: ##STR10## wherein R and R' are each, independently, selectedfrom hydrogen, alkyl and substituted alkyl and X is a bridging meansselected from divalent aliphatic, cycloaliphatic, and aromatic groups.

These compounds may be prepared in accordance with the methods describedin U.S. Pat. Nos. 2,723,265 and 3,290,350 both of said patents beingspecifically incorporated herein by reference, and for example, byreacting isocyanic acid with compounds having a plurality of vinylidenegroups.

Examples of poly aliphatic isocyanate compounds for use in the rapidlycurable compositions of this invention include:

α,α'-dimethyl-p-xylylene diisocyanate,

α,α,α',α'-tetramethyl-m-xylylene diisocyanate,

α,α,α',α'-tetramethyl-p-xylylene diisocyanate,

bis(4-(1-isocyanato-1-methylethyl) phenyl) methane,

α-ethyl-α'-methyl-p-xylylene diisocyanate,

2,6-bis (1-isocyanato-1-methylethyl) naphthalene,

1,4-bis (1-isocyanato-1-methylethyl) cyclohexane,

1,3-bis (1-isocyanato-1-methylethyl) cyclohexane,

1,8-diisocyanato-p-menthane, isophorone diisocyanate,

bis(4-isocyanatocyclohexyl)methane ("H₁₂ MDI") and the like.

In addition to the above described monomeric aliphatic isocyanatecompounds, polymeric materials derived in part from these aliphaticisocoyanates and possessing terminal aliphatic isocyanate groups mayalso be used as component (a) (i). The polymeric materials containingaliphatic isocyanate terminal groups are polymeric adducts or urethaneprecursors, formed by reacting an excess of poly aliphatic diisocyanatecompound, generally about 1 molar equivalent, with a polyol compound,generally 0.3 to about 0.7 molar equivalents, in a suitable solvent attemperatures of about 70°-80° C. for several hours, although if acatalyst is used, such as an organic tin catalyst, in an amount of fromabout 0.005 to 0.1 percent by weight, reaction times may be considerablyreduced.

Suitable polyols which may be reacted with the polyaliphatic isocyanatecompounds to form isocyanate terminated urethane precursors include:monomeric polyols such as ethylene glycol, propylene glycol, diethyleneglycol, triethylene glycol, dipropylene glycol, trimethylene glycol, and1,3- and 1,4- butanediol.

Polyether polyols, which are obtained by effecting addition of one type,or two types or more, among, for example, ethylene oxide, propyleneoxide, butylene oxide, tetrahydrofuran, and styrene oxide, with forexample, ethylene glycol, propylene glycol, diethylene glycol,triethylene glycol, dipropylene glycol, trimethylene glycol, 1,3- and1,4- butanediol, 1,5-pentanediol, 1,2-hexylene glycol, 1,10-decanediol,1,2-cyclohexanediol, 2-butene-1,4-diol, 3-cyclohexene-1,1-dimethanol,4-methyl-3-cyclohexene-1,1-dimethanol, 3-methylene-1,5-pentanediol,(2-hydroxyethoxy)-1-propanol, 4-(2-hydroxyethoxy)-1-butanol,5-(2-hydroxypropoxy)-1-pentanol, 1-(2-hydroxymethoxy)-2-hexanol,1-(2-hydroxypropoxy)-2-octanol, 3-allyloxy-1,5-pentanediol,2-allyloxymethyl-2-methyl-1,3-pentanediol,(4,4-pentyloxymethyl)-1,3-propanediol,3-(o-propenylphenoxy)-1,2-propanediol, 2,2'-diisopropylidenebis(p-phenyleneoxy) diethanol, glycerin, 1,2,6-hexanetriol,1,1,1-trimethylolethane,1,1,1-trimethylolpropane,3-(2-hydroxyethoxy)-1,2-propanediol,3-(2-hydroxypropyl)-1,2-propanediol,2,4-dimethyl-2-(2-hydroxyethoxy)-methylpentanediol-1,1,1-tris((2-hydroxyethoxy)methyl)-ethane, 1,1,1-tris ((2-hydroxypropoxy)methyl)propane, pentaerythritol, sorbitol, sucrose, lactose, α-methylglucoside, α-hydroxyalkyl glucosides, novolak resin, phosphoric acid,benzenephosphoric acid, polyphosphoric acids, such as tripolyphosphoricacid and tetrapolyphosphoric acid; and polycaprolactone may also beemployed.

Polyester polyols formed from one type, or two types or more, amongcompounds which possess at least two hydroxy groups, such aspolytetramethylene ether glycol, also ethylene glycol, diethyleneglycol, triethylene glycol, 1,2-propylene glycol, dipropylene glycol,trimethylene glycol, 1,3- and 1,4- butanediol, tetramethylene glycol,neopentyl glycol, hexamethylene glycol, decamethylene glycol, glycerin,trimethylolpropane, hexanetriol, pentaerythritol, and sorbitol, and onetype, or two types or more, among compounds which possess at least twocarboxyl groups, such as malonic acid, maleic acid, succinic acid,adipic acid, tartaric acid, pimelic acid, sebacic acid, oxalic acid,phthalic acid, terephthalic acid, and hemimellitic acid can also beused.

Also ring-opened polymers of cyclic esters such as polycaprolactone; andfurthermore, there are so-called polymer polyol compositions amongpolyether polyols and/or polyester polyols which can be obtained bypolymerizing ethylenically unsaturated compounds, and as ethylenicallyunsaturated compounds which are suitable in preparing such compositions,there are for example acrylonitrile and styrene. One can further use,for example, 1,2-polybutadiene glycol, 1,4-polybutadiene glycol,polyhydroxy polyacrylates, and epoxy resins.

The polymeric isocyanate terminated urethane precursors may be usedalone or they may be further reacted with still another monomeric orpolymeric compound containing hydroxyl groups as component (a) (ii).

Component (a) (ii) may comprise any of the polyhydroxy compoundsdescribed above for forming the polymeric urethane precursors for use ascomponent (a) (i). In this way, for example, a polyether adduct may befurther reacted with a polyester polyol or polycaprolactone toincorporate desired end properties into the polyurethane composition,such as for example, increased flexibility or elastomeric properties.

The rapid cure polyurethane compositions of this invention also containfrom about 0.01 to about 10 parts by weight of catalyst composition (b).A preferred catalyst composition consists essentially of a 50--50 weightmixture of lead naphthenate to dialkyltin dicarboxylate.

Generally, the aliphatic isocyanate component and polyol component aremixed and thereafter the catalyst composition is added immediatelybefore use. Alternatively, the catalyst may be added as one componentpreferably, the polyol coxponent, some time before use. On mixing in thecatalyst, and after gentle heating to about 30° C. to 100° C., thecompositions rapidly react to form polyurethane compositions which gelin a matter of a few seconds to a few minutes.

The new and improved highly reactive rapid cure aliphatic-isocyanatebased polyurethane compositions of this invention may be mixed andgently heated to form a variety of polyurethane products, for example,coatings and injection molded products suitable for handling inaccordance with conventional polyurethane technology.

The improved cure rates provided by the new and improved catalystmixture of the present invention make it possible to provide integralskin foam polyurethane compositions and products which are based onaliphatic isocyanates and therefore do not yellow or discolor uponexposure to sunlight or other sources of ultra violet light.

In accordance with this especially preferred aspect of the invention,new and improved injection moldable poly aliphatic isocyanate basedintegral skin foam polyurethane compositions are provided. The injectionmoldable integral skin foam compositions of this invention comprise:

(a) a poly aliphatic isocyanate compound or a prepolymer adductpossessing polyaliphatic isocyanate functionality;

(b) a mixed polyol component comprising:

(i) from about 50 to about 100 parts by weight of a vinylmonomer-grafted polymeric polyol having an hydroxyl value of about 20 toabout 60; and

(ii) from about 50 to about 0 parts by weight of a polyether polyolhaving an hydroxyl value of about 20 to 60, per 100 parts by weight ofsaid polyol mixture;

(c) an effective amount of a crosslinking agent, comprising a mixture ofan amino alcohol and ethylene glycol or a low molecular weight adduct ofethylene oxide and a polyol compound in a weight ratio of about 1:3 toabout 3:1 respectively;

(d) a minor effective amount of the lead naphthenate/dialkyltindicarboxylate catalyst composition; and

(e) an effective amount of a foaming agent.

In accordance with this embodiment, the aliphatic isocyanate compound orpoly aliphatic-isocyanate functional prepolymer adduct is the same as isdescribed in connection with component (a) (i) above.

Mixed polyol component (b), firstly comprises (i) from 50 to 100 partsby weight, based on the total weight of (b) of a vinyl monomer-graftedpolymeric polyol having an hydroxyl value of about 20 to 60.

These grafted polymeric polyols may be prepared in accordance with knownmethods by polymerizing a vinyl monomer in a polyether polyol. Suitablevinyl monomers for use in forming the grafted polymeric polyol are, forexample, styrene, α-methyl styrene, methyl methacrylate, acrylonitrileand the like, and mixtures of two or more of these vinyl monomers may beused. The vinyl monomer is generally added to the polyether polyol in anamount of from about 10 to about 30 parts by weight, per 100 parts byweight of the polyether polyol.

The polyether polyols for use in components (b) (i) and (b) (ii)comprise either: a polyether polyol possessing two OH groups, obtainedby addition polymerizing at least one of ethylene oxide, propylene oxideand butylene oxide toward water or diols such as ethylene glycol,diethylene glycol, triethylene glycol, propylene glycol, dipropyleneglycol, butanediol or hexanediol; or polyether polyols possessing from 3to 8 OH groups, which are obtained by addition polymerizing at least oneof the lower alkylene oxides toward a polyhydric alcohol, such asglycerol, trimethylol propane, hexanetriol, pentaerythritol, α-methylglucoside, sorbitol and sucrose. The polyether polyol, whetherpossessing two OH groups or 3-8 OH groups, should have an overallhydroxyl number of about 20 to about 60. If the OH value is lower thanthis range, the reactivity of the polyether polyol decreases. Higher OHvalues generally yield integral skin foams which are too hard, forfurniture coverings, for example.

The grafted polymeric polyol and the polyether polyols are mixed toprovide the mixed polyol component (b). Generally, the grafted polymerpolyol is present in component (b) in an amount of from 50 to 100 partsby weight and the polyether polyol is added in an amount of from 50 to 0parts by weight based on the total weight of component (b). It has beendiscovered that if less than 50 parts of grafted polymeric polyol areused in component (b) the strength and load-supporting capability of theintegral skin foam decrease and the air permeability and skinkage of thefoam increase.

The new and improved integral skin foam compositions additionallycomprise as component (c) a crosslinking agent comprising a mixture ofat least one amino alcohol and lower alkylene glycol or a low molecularweight ethylene oxide adduct of a 3 to 6 hydric polyol.

More particularly, crosslinking agent (c) comprises an amino-alcoholselected from monoethanolamine, diethanolamine and triethanolamine, ormixtures thereof, with a lower, e.g., C₁ -C₆ alkylene glycol such asethylene glycol, butanediol, hexanediol and the like, or an ethyleneoxide adduct of a polyhydric alcohol having from 3 to about 6 hydroxylgroups, for example glycerol, trimethylolpropane, 1,3,6-hexanetriol,pentaerythritol and sorbitol. In the ethylene oxide adduct generally theethylene oxide is added in an amount sufficient to provide a molar ratioof ethylene oxide to poly hydric alcohol of from about 1:1 to about 2:1,respectively.

The weight ratio of the amino alcohol to either the lower alkyleneglycol or low molecular weight polyol is preferably from about 3:1 toabout 1:3.

Crosslinking agent (c) is added in an effective crosslinking amount andpreferably is added in an amount of from about 5 to about 25 parts byweight based on 100 parts by weight of the mixed polyol component (b).This quantity of crosslinking agent is preferred because if less than 5parts of crosslinker are used, same basis, longer molding cycle timesare required and the load-bearing capabitites of the cured skin foamproduct decreases. If more than 25 parts of the crosslinking mixture areadded, same basis, the integral skin foam becomes hard and inelastic,rendering it less suitable for such uses as armrests and seat covers inthe interior of an automobile, for example.

The new and improved integral skin foam compositions will generallycontain a molar ratio of the total isocyanate groups in (a) to the totalof hydroxyl groups in (b) and (c) combined of from about 1:0.9 to about1:1.2, respectively.

Catalyst component (d) for use in the integral skin foam composition ofthis invention is the same lead naphthenate/dialkyltin dicarboxylatemixture as is defined above.

Foaming agent (e) herein, may comprise any of the conventional foamingagents which are inert to the isocyanate reactants. More particularly,foaming agent (e) will comprise a low-boiling halogenated hydrocarbon,known to those skilled this art, for example, methylene cloride,trichloromonofluoromethane, C₅ to C₇ hydrocarbons and the like. Thefoaming agents can be added in conventional amounts and generally willbe added in amounts of from about 10 parts to about 30 parts by weightbased upon the weight of the overall composition.

The new and improved integral skin foam compositions of the present mayalso include other additives such as antioxidants, UV stabilizers,fillers, plasticizers, flame retardants, UV absorbers, dyes, pigmentsand the like, all of said additives being incorporated in theirconventional amounts, e.g., from about 0.2 to about 2.0 parts by weight,per 100 parts by weight of mixed polyol component (b).

More particularly, the integral skin foam compositions of this inventionmay optionally contain antioxidant compounds which comprise varioushindered phenols. Hindered phenolic antioxidants are abundantlyavailable, for example, under the tradenanes IRGANOX 1010 and IRGANOX1076 from Ciba-Geigy Company. As UV absobers various benzotriazoles maybe employed. Commercially available compounds of this type are forexample TINUVIN P, TINUVIN 327 and TINUVIN 329 from Ciba-Geigy Company.Suitable amime--type U.V. stabilizers may also be employed such as thosesold under the tradenames TINUVIN 144, TINUVIN 120 and IRGASTAB 2002,from Ciba-Geigy Company.

In practice, the new and improved integral skin foam compositions ofthis invention are prepared by first admixing mixed polyol component(b), crosslinking agent (c), catalyst mixture (d), foaming agent (e) andany optional additives such as dyes, pigments, and/or stabilizers toform a resin solution. Thereafter, the polyisocyanate orisocyanate-terminated prepolymer adduct,(a), is added to the resinsolution and the solution is thoroughly mixed. The mixed ingredients areimmediately poured into a mold and are gently heated to about 30° C. to100° C. to effect foaming and curing. In commercial practice, acoventional foam injection molding machine may be employed. Afteradmixture and upon gentle heating for about 1 to about 5 minutes, theintegral skin foam shaped article may be removed from the mold.

The new and improved integral skin foam compositions of the presentinvention exhibit sufficiently rapid cure rates, such that they are wellsuited for use in high speed reaction injection molding applications.The integral skin foam shaped articles prepared from the compositionsdescribed herein, exhibit good strength and load-bearing capabilities.They may readily be dyed or pigmented to take on light or bright colorshades and do not exhibit yellowing or discoloration upon extendedexposure to ultraviolet light.

In order that those skilled in the art may better understand how thepresent invention may be practiced, the following examples are providedby way of illustration and not by way of limitation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 1

A mixture of 10 grams of dry polytetramethylene ether glycol (OH No.56.1, mol. wt. 2000), 0.89 grams of α,α,α',α'-tetramethyl-m-xylylenediisocyanate, 3.66 grams of trimethylol propane, and 1.5 ml. of drytoluene was warmed to 73°-75° C. The warm solution was immediatelyplaced in a calorimeter. To the solution was added with vigorousstirring 3.6 ml. of a 4% solution of catalyst in dry toluene (1% byweight, based on the weight of polymer reactants). The tempertureinitially dropped to 70° C. and was followed by an exotherm and anincrease in the viscosity of the solution. The peak temperature (°C.)and the time (minutes) to cessation of flow (gelation time) wererecorded. The gelation time provides a measure of catalyst efficiency,with shorter gelation time values indicating greater catalysteffectiveness. The following data were obtained.

                  TABLE 1                                                         ______________________________________                                                        Peak Tempera-                                                                             Gelation Time,                                    Catalyst        ture, °C.                                                                          Min.                                              ______________________________________                                        Lead naphthenate (LN)                                                                         89          3.5                                               Dimethyl tin dilaurate                                                                        94          2.3                                               (DMTDL)                                                                       50/50 LN/DMTDL  96          0.6                                               ______________________________________                                    

The data clearly show a marked increase in efficiency, as mainfested byreduced gelation time, of the 50/50 catalyst composition.

EXAMPLE 2

The procedure of Example 1 was followed except that dibutyl tindilaurate (DBTDL) was used instead of dimethyl tin dilaurate. Thefollowing data were obtained.

                  TABLE 2                                                         ______________________________________                                                     Peak                                                             Catalyst     Temperature, °C.                                                                    Gelation Time, Min.                                 ______________________________________                                        LN           89           3.5                                                 DBTDL        94           4.6                                                 50/50-LN/DBTDL                                                                             98           1.1                                                 ______________________________________                                    

The data again shows the increased efficiency of the catalystcomposition of the invention.

EXAMPLE 3

The procedure of Example 1 was followed except that 3.33 grams ofisophorone diisocyanate was used instead of 0.89 gram ofα,α,α',α'-tetramethyl-m-xylylene diisocyanate. The following data wereobtained.

                  TABLE 3                                                         ______________________________________                                                     Peak                                                             Catalyst     Temperature, °C.                                                                    Gelation Time, Min.                                 ______________________________________                                        LN           100          2.10                                                DMTDL        96           3.60                                                50/50-LN/DMTDL                                                                             97           1.05                                                ______________________________________                                    

EXAMPLE 4

The procedure of Example 1 was followed except that 3.22 grams of1,8-diisocyanate-p-menthane was used instead of 0.89 gram ofα,α,α',α'-tetramethyl-m-xylylene diisocyanate. The following data wereobtained.

                  TABLE 4                                                         ______________________________________                                                     Peak                                                             Catalyst     Temperature, °C.                                                                    Gelation Time, Min.                                 ______________________________________                                        LN           81           45                                                  DMTDL        80           65                                                  50/50-LN/DMTDL                                                                             85            4                                                  ______________________________________                                    

PREPARATIONS A and B PREPARATION OF POLYMER POLYOL A

A polymer polyol, was obtained by graft polymerizing 20 parts of anequipolar mixture of acrylonitrile and styrene to 80 parts of apolyether polyol of OH value 34 which was obtained by adding propyleneoxide to glycerin and by next adding ethylene oxide.

PREPARATION OF PREPOLYMER ADDUCT B

An isocyanate-group-terminated prepolymer whose NCO group contentquantity was 24.5 weight % (henceforth % will represent weight %) andwhose viscosity was 90 cps/25° C., and was obtained by reacting 25 partsof a polyether polyol of OH value 34, which was obtained by polymerizingpropylene oxide and ethylene oxide with pentaerythitol, with 75 parts ofm-tetramethylxylyene diisocyanate (m-TMXDI).

EXAMPLE 5

A resin solution was obtained by thoroughly mixing 100 parts of polymerpolyol A, 10 parts of a crosslinking agent consisting of ethylene glycol6 parts and diethanolamine 4 parts, 4 parts of a catalyst consisting oflead naphthenate (lead content 24%) 3 parts and dimethyltin dilaurate 1part, monochlorotrifluoromethane foaming agent 14 parts, and 2.0 partsof antioxidants/stabilizers.

Thereafter, m-tetramethylxylylene diisocyanate(m-TMXDI) 45.8 parts wasadded to this resin solution and after vigorously mixing for 5 seconds,this was poured into a mold at 65° C. Table 5 shows the results ofmeasurement of the physical properties of the integral skin foam whichwas obtained by unmolding after letting this stand for 5 minutes.

                  TABLE 5                                                         ______________________________________                                        Density          g/cm.sup.3   0.432                                           100% tensile modulus                                                                           kg/cm.sup.2  14.4                                            Tensile strength kg/cm.sup.2  23.6                                            Elongation       %            168                                             Tear resistance  kg/cm        12.7                                            Surface hardness "Ascaa"* type C                                                                            68                                              Light resistance test                                                                          Fade-ometer  No change                                                        500 hours                                                    ______________________________________                                         *Automobile Seat Cover Association of America                            

This integral skin foam did not undergo discoloration from extendedexposure to ultra violet light, and it is clear from Table 5 that itsstrength was excellent and that it had a modulus and surface hardnesswhich were adequately capable of withstanding load. When leadnaphthenate or dimethyltin dilaurate was each used alone in the amountof 4 parts as the catalyst, not only was a long time necessary in orderto remove the molded product from the mold but the surface of the moldedproduct was sticky and the desired surface hardness could not beobtained.

EXAMPLE 6

A resin solution was prepared in accordance with Example 5 containing100 parts of prepolymer A, 9 parts of a mixture consisting of ethyleneglycol 6 parts and diethanolamine 3 parts as the crosslinking agent, and2.5 parts of a mixture consisting of 2.0 parts of lead naphthenate (leadcontent 24%) and 0.5 parts of dimethyltin dilaurate as the catalyst.

The isocyanate component used comprised 56.6 parts of a prepolymer whoseisocyanate content was 25.3%, which was obtained from a polyether polyolof OH value 34, which was obtained by addition polymerizing propyleneoxide and ethylene oxide onto pentaerythritol, and IPDI.

The physical properties of the integral skin foam obtained when thesetwo components were treated as in Example 5 are as shown in Table 6.

                  TABLE 6                                                         ______________________________________                                        Density          g/cm.sup.3   0.581                                           100% tensile modulus                                                                           kg/cm.sup.2  37.0                                            Tensile strength kg/cm.sup.2  39.8                                            Elongation       %            112                                             Tear resistance  kg/cm        14.2                                            Surface hardness Ascaa type C 88                                              Light resistance test                                                                          Fade-ometer  No change                                                        500 hours                                                    ______________________________________                                    

It is clear from Table 6 that this integral skin foam did not undergodiscoloration by light and that it excelled in mechanical properties.

EXAMPLE 7

A resin solution was obtained by thoroughly mixing 60 parts of polymerpolyol A, 40 parts of the polyether polyol which was the productionintermediate for polymer polyol A, 10 parts of a crosslinking agentconsisting of ethylene glycol 6 parts and diethanolamine 4 parts, 2.5parts of a catalyst consisting of lead naphthenate (lead content 25%) 2parts and dimethyltin dilaurate 0.5 and 2.0 parts ofantioxidants/stabilizers.

The isocyanate component used comprised 66.2 parts of a prepolymer ofisocyanate content 24.0%, which was produced from a polyether polyol ofOH value 34, which was obtained by addition polymerizing propylene oxideand ethylene oxide onto pentaerythritol, and H₁₂ MDI.

The physical properties of the integral skin foam which was obtained bythereafter treating as in Example 5 were as given in Table 7.

                  TABLE 7                                                         ______________________________________                                        Density          g/cm.sup.3   0.567                                           50% tensile modulus                                                                            kg/cm.sup.2  23.7                                            Tensile strength kg/cm.sup.2  33.7                                            Elongation       %            80                                              Tear resistance  kg/cm        11.2                                            Surface hardness Ascaa type C 81                                              Light resistance test                                                                          Fade-ometer  No change                                                        500 hours                                                    ______________________________________                                    

It is clear from Table 7 that this integral skin foam did not undergolight resisting discoloration, and that it had excellent strength.

EXAMPLE 8

A resin solution component was obtained in accordance with the method ofExample 5, 14 parts of a crosslinking agent consisting of ethyleneglycol 6 parts, diethanolamine 4 parts, and triethanolamine 4 parts.

The isocyanate component used comprised 76 parts of prepolymer A insteadof m-TMXDI.

Using a high pressure foaming machine, model NR-230, made by Toho KikaiCompany, Ltd., the composition was injection molded into a mold of innercapacity 300×500×10 mm which had been warmed to 65° C. The flow quantityratio (weight) of the resin component and the isocyanate component wascaused to be 135:76.

The product was removed from the mold after 2 minutes, and a goodintegral skin foam molded product was obtained. As a result ofmeasurement of the physical properties of this article, not only did itnot undergo light resisting discoloration but it had sufficientstrength, as is indicated in Table 8.

                  TABLE 8                                                         ______________________________________                                        Density          g/cm.sup.3   0.571                                           100% tensile modulus                                                                           kg/cm.sup.2  25.7                                            Tensile strength kg/cm.sup.2  32.1                                            Elongation       %            128                                             Tear resistance  kg/cm        12.1                                            Surface hardness Ascaa type C 83                                              Light resisting test                                                                           Fade-ometer  No change                                                        500 hours                                                    ______________________________________                                    

When lead naphthenate or dimethyltin dilaurate each was used alone inthe amount of 4 parts as the catalyst, not only was much time necessaryin order to remove the molded product from the mold but the surface ofthe molded product was sticky and the desired surface hardness could notbe obtained.

Although the present invention has been described with reference tocertain preferred embodiments, it is apparent that modifications andchanges may be made there in by those skilled in this art, withoutdeparting from the scope and spirit of this invention as defined by theappended claims.

What is claimed is:
 1. A highly reactive, rapidly curable polyurethanecomposition, said composition comprising:(a) a mixture or a prepolymerof:(i) a poly aliphatic isocyanate compound of the formula: ##STR11##wherein R and R' are each, independently, selected from hydrogen, alkylor substituted alkyl and X is a bridging means selected from aliphatic,cycloaliphatic or aromatic groups, or a prepolymer adduct of saidisocyanate compound possessing poly aliphatic isocyanate functionality;and (ii) a monomeric or polymeric compound containing a plurality ofhydroxyl groups, the molar ratio of the total amount of said isocyanatein (i) to the total amount of hydroxyl groups in (ii) being from about1:0.8 to about 1:1.2, respectively; and (b) a minor effective amount ofa catalyst composition, said composition consisting essentially of(i)from about 25 to about 75 parts by weight of lead naphthenate; and (ii)from about 75 to about 25 parts by weight of at least one dialkyltindicarboxylate compound of the formula: ##STR12## wherein R is selectedfrom C₁ to C₈ alkyl and R' is selected from C₁ to C₁₈ alkyl, based upon100 parts by weight of the catalyst composition.
 2. A polyurethanecomposition as recited in claim 1, wherein said aliphatic isocyanatecompound component (a) (i) comprises α, α,α',α'-tetramethyl-m-xylylenediisocyanate.
 3. A polyurethane composition as recited in claim 1,component (a) (i) comprises a polymeric adduct of a polyaliphatic-isocyanate compound and an hydroxyl-terminated polyether, saidadduct having aliphatic isocyanate terminal groups.
 4. A polyurethanecomposition as defined in claim 1, component (a) (i) comprises apolymeric adduct of a poly aliphatic isocyanate compound and anhydroxyl-terminated polyester, said adduct having aliphatic isocyanateterminal groups.
 5. A polyurethane composition as defined in claim 1,wherein component (b) (ii) comprises a dialkyltin dicarboxylate selectedfrom dimethyltin dilaurate or dibutyltin dilaurate.
 6. A polyurethanecomposition as defined in claim 1, wherein the weight ratio of component(b) (i) to (b) (ii) is about 50:50.
 7. A polyurethane composition asdefined in claim 1, wherein catalyst composition (b) is present in anamount of from about 0.01 to about 10 parts by weight, based on 100parts by weight of (a).
 8. A polyurethane composition as defined inclaim 1, wherein catalyst composition (b) is present in an amount offrom about 0.05 to about 5.0 parts by weight, based on 100 parts byweight of (a).
 9. A process for catalyzing reactions between polyaliphatic isocyanate compounds and compounds possessing a plurality ofhydroxyl groups, said process comprising:(a) providing a reactionmixture of(i) a poly aliphatic isocyanate compound of the formula:##STR13## wherein R and R' are each independently, selected fromhydrogen, alkyl and substituted alkyl and X is a bridging means selectedfrom aliphatic, cycloaliphatic or aromatic groups, or a prepolymeradduct of said isocyanate compound possessing poly aliphatic isocyanatefunctionality; and (ii) a monomeric or polymeric compound containing aplurality of hydroxyl groups; and molar ratio of the total isocyanategroups in (i) to the total of hydroxyl groups in (ii) being from about1:0.8 to about 1:1.2, respectively; and (b) thereafter adding a minoreffective amount of a catalyst composition to said reaction mixture,said catalyst composition consisting essentially of:(i) from about 25 toabout 75 parts by weight of lead naphthenate; and (ii) from about 75 toabout 25 parts by weight of a dialkyltin dicarboxylate compound of theformula: ##STR14## wherein R² is selected from C₁ to C₈ alkyl and R³ isselected from C₁ to C₁₈ alkyl, based on 100 parts by weight of saidcatalyst composition; and (c) allowing the mixture of step (b) to react.10. A process as recited in claim 9 wherein step (c) comprises gentlyheating the catalyzed reaction mixture of step (b) to from about 30° toabout 100° C. and permitting said reaction to proceed untilsubstantially complete.